The present invention relates generally to methods, systems and devices for the removal of tissue and relates more particularly to methods, systems, and devices well-suited for the removal of uterine fibroids and other abnormal gynecological tissues.
It is believed that uterine fibroids occur in a substantial percentage of the female population, perhaps in at least 20 to 40 percent of all women. Uterine fibroids are well-defined, non-cancerous tumors that are commonly found in the smooth muscle layer of the uterus. In many instances, uterine fibroids can grow to be several centimeters in diameter and may cause symptoms like menorrhagia (prolonged or heavy menstrual bleeding), pelvic pressure or pain, and reproductive dysfunction.
Current treatments for uterine fibroids include pharmacological therapy, hysterectomy, uterine artery embolization, and hysteroscopic resection. Pharmacological therapy typically involves the administration of NSAIDS (non-steroidal anti-inflammatory drugs), estrogen-progesterone combinations, and GnRH (gonadotropin releasing hormone) analogues. However, current pharmacological therapies are largely ineffective and merely palliative. By comparison, a hysterectomy involves the surgical removal of the uterus from a patient. For this reason, a hysterectomy represents a highly effective way of ridding a patient of uterine fibroids. As a result, several hundred thousand hysterectomies are typically performed annually in the United States to treat uterine fibroids. However, despite their widespread use, hysterectomies also possess certain disadvantages, such as a loss of fertility, sexual dysfunction, and the risks commonly associated with a major surgical procedure, such as hemorrhaging, lesions, infections, pain and prolonged recovery. Uterine artery embolization involves inserting a catheter into a femoral artery and then guiding the catheter to a uterine fibroid artery. Small particles are then injected from the catheter into the fibroid artery, blocking its blood supply and causing it to eventually shrink and die. Although this procedure is less invasive than a hysterectomy, it often results in pain-related, post-surgical complications. Moreover, the physicians that are trained to perform uterine artery embolization are typically interventional radiologists, as opposed to physicians trained specifically to take care of gynecological problems, whereas the physicians trained specifically to take care of gynecological problems typically do not possess the skill to perform catheter-based uterine artery embolization.
Hysteroscopic resection typically involves inserting a hysteroscope (i.e., an imaging scope) into the uterus through the vagina, i.e., transcervically, and then cutting away the fibroid from the uterus using a device delivered to the fibroid by the hysteroscope. Hysteroscopic resections typically fall into one of two varieties. In one variety, an electrocautery device in the form of a loop-shaped cutting wire is fixedly mounted on the distal end of the hysteroscope—the combination of the hysteroscope and the electrocautery device typically referred to as a resectoscope. The transmission of electrical current to the uterus with a resectoscope is typically monopolar, and the circuit is completed by a conductive path to the power unit for the device through a conductive pad applied to the patient's skin. In this manner, tissue is removed by contacting the loop with the part of the uterus wall of interest. Examples of such devices are disclosed, for example, in U.S. Pat. No. 5,906,615, inventor Thompson, issued May 25, 1999.
In the other variety of hysteroscopic resection, an electromechanical cutter is inserted through a working channel in the hysteroscope. Tissue is then removed by contacting the cutter, which typically has a rotating cutting instrument, with the part of the uterus wall of interest. Examples of the electromechanical cutter variety of hysteroscopic resection are disclosed in, for example, U.S. Pat. No. 7,226,459, inventors Cesarini et al., issued Jun. 5, 2007; U.S. Pat. No. 6,032,673, inventors Savage et al., issued Mar. 7, 2000; U.S. Pat. No. 5,730,752, inventors Alden et al., issued Mar. 24, 1998; U.S. Patent Application Publication No. US 2006/0047185 A1, inventors Shener et al., published Mar. 2, 2006; and PCT International Publication No. WO 99/11184, published Mar. 11, 1999, all of which are incorporated herein by reference.
In both of the above-described varieties of hysteroscopic resection, prior to fibroid removal, the uterus is typically distended to create a working space within the uterus. (Such a working space typically does not exist naturally in the uterus because the uterus is a flaccid organ. As such, the walls of the uterus are typically in contact with one another when in a relaxed state.) The conventional technique for creating such a working space within the uterus is to administer a fluid to the uterus through the hysteroscope under sufficient pressure to cause the uterus to become distended. Examples of the fluid used conventionally to distend the uterus include gases like carbon dioxide or, more commonly, liquids like water or certain aqueous solutions (e.g., a saline solution or a sugar-based aqueous solution). Where resection is effected using a resectoscope, it is typically necessary that the distending fluid not be current-conducting so that electricity is not conducted to undesired locations. However, because the distending fluid is administered under pressure (which pressure may be as great as 120 mm Hg or greater), there is a risk, especially when tissue is cut, that the distending fluid may be taken up by a blood vessel in the uterus, i.e., intravasation, which uptake may be quite harmful to the patient. Because excess intravasation can lead to death, it is customary to monitor the fluid uptake on a continuous basis using a scale system.
Nevertheless, despite the aforementioned risks of intravasation, with proper monitoring of fluid uptake, hysteroscopic resection is a highly effective and safe technique for removing uterine fibroids. However, one shortcoming with hysteroscopic resection is that it typically requires that anesthesia be administered to the patient. This is because conventional resectoscopes typically have a diameter in excess of 7 mm and because conventional hysteroscopes of the type through which mechanical cutter-type devices are inserted typically have a diameter of about 9 mm. By contrast, the cervix typically cannot be dilated to a diameter greater than about 5.5 mm without causing considerable discomfort to the patient. As a result, due to the need for anesthesia, hysteroscopic resection is typically performed in a hospital operating room and, as a result, bears a large cost due to the setting and the support personnel required.